Control system.



C. RENSHAW,

CONTROL SYSTEM APPLICATION map um 9.1914.

y UNITED sra'rns rari;

onirica CLARENCE RENSHAW, 0F EDGEWGOB ARK, PENNSYLVANIA, ASSIGNOR TO 'WESTING- HOUSE ELECTRIC ANI) MANUFACTURING COMPANY, A CQRPORATL'ON OF PENNSYL- VANIA.

CONTRL SYSTEM.

Application led June 9, 1914.

To all iowm may concern:

Be it known that I, CLARENCE RnNsHsw, a citizen of the United States, and a resident of Edgewood Park, in the county of Allegheny and State of Pennsylvania, have linvented a new and useful Improvement in Control Systems, of which. the following is a specification.

My invention relates to systems of control, and it has special reference to the control of electric motors that are adapted to propel electric railway vehicles or the. like.

rlhe object of my invention is to provide f a control system of the above-indicated charticular, requires only minor changes in the controller that is usually employed, in 'Y order to adapt it for lield control.

.ln the prior art, control systems of the field control type have required the use of certain specially constructed, and, conscquently', expensive apparatus. By employing my invention, however, the same apparatus ordinarily employed for non-field control systems, may be readily used with field-'control motors when supplemented by simple additional devices that are adapted to delay the actuation of the field changeover switches until the motor current has decreased to a predetermined value, thereby f preventing any abnormal rush of current and insuring a steady and smooth acceleration.

"In the accompanying drawing, Figure 1 is a diagrammatic view of a system of control embodying my invention, the main circuits and the auxiliary controh` circuits being shown segregated, for purposes of simplicity and clearness, and Fig. 2 is a chart of well-known form showing the sequence v Specification of Letters latent.

Patented July 4, 1916.

Serial No. 843,939.

of operation of the switches illustrated in Fig. l.

iieferring to the drawing, the system here shown comprises a pair of supply-circuit conductors respectively marked Trolley and LGround"; a plurality of electric motors respectively having armatures A1 and A2 and subdivided series field windings F1 and F2; field changeover switches l and 2 for excluding predetermined portions of the field windings Fl and F 2 from circuit, under predetermined conditions; a plurality of commonly mechanically actuated reversing switches RS of the usual type that are respectively electrically associated with the ield windings F1 and F2; an accelerating resistor AR, the sections of which are adapted to be suitably manipulated by a plurality of switches Rl, R2, ll and R of a familiar type; a plurality of similar motor-operating switches LS, l), Sr, and G; a plurality of double-.throw motor cutout switches CO1 and CO2, for respectively excluding the motors from circuit when thrown to one of `their operative positions; an overload trip switch marked T, for the purpose of interrupting the control circuit-s under predetermined abnormal conditions; and a limit switch L, of a familiar type, that is associated with the field change-over switches l and 2, as hereinafter described.

The auxiliary control circuits shown coinprise a master controller MC of familia;1 construction that is adapted to occupy a plu rality of motor-operating,positions l to?I 9, inclusive; a master reverser MR that is adapted to occupy a forward, an oft and a reverse position; a plurality of magnet coils F and R for operating the reversing switches RS; a plurality of magnet coils for actuating the several circuit switches illustrated in Fig. l, when energized through the master controller MC; a plurality of train line conductors TL for suitably connecting the master controller to the several magnet coils; a control resistor CR which is connected across the supply circuit and from portions of which the various magnet coils may be energized; a magnet coil marked Field changeover, which, when. energized, is adapted to simultaneously actuate the field change-over switches l and 2 from the usual full ield position to the normal field position, in a well-known inanner; and a plurality of interlocking contact members that are respectively designated with regard to the particular switch by which each member is adapted to be actuated.

The operation. of my control system may 'Je described as follows: Assuming the master controller MC to be moved to its position l, and the master reverser to be thrown to its forward position, a circuit is first established from the trolley through a conductor 3, control fingers and -which are bridged by a contact member 6 of the master controller-a conductor 7 and the control resistor CR to the negative conductor ground. Another circuit is thereupon established from an intermediate point in the control resistor to the conductor S, the actuating coil of the switch LS, conductors t) and l0, control fingers 1l and lf2- which are bridged by Contact member ,13 of the main reversing switches RS-conductor 14;, control fingers l5 and l-which are bridged by a Contact member 17 of a master reverser-and a conductor 18 to ground. Another circuit is simultaneously established from the conductor 8 through conductors i9, 2O and 2l,.control fingers 22 and 23-which are bridged by a Contact member 24; of the master eontrollermconductor 25, an interlocking contact member marked P-out and the actuating coil of the switch S to the conductors 26 and gi-ormai. A third control circuit is also established from a second intermediate point in the Vcontrol resistor through conductor 27, coperating stationary and movable contact members 28 of' the overload trip switch GT., the actuating coil of the. switch R1, conductor :9.9 and control linger 30, which engages the energized contact member 30a of the master controller. The switches LS, Fi and R1 are thus closed, whereby the motors are connected vin series-circuit relation, with all of the accelerating resistor AR included in the circuit.

lf the master controller is moved to its position 2, the contact member 24 engages a control iinger 3l whence circuit is comple-ted through conductor 32, the actuating coil oi the switch R2, coperating stationary and movable Contact members 33 of the overload trip switch OT and the conductor 27 to the control resistor CR. The switch R2 thus closed and the switch Rl is substantially simultaneously opened by reason of the disengagement of the control finger 30 and the contact member' 30, whereby a certain section ofthe accelerating resistor AR 1s excluded from circuit to accelerate the motors.

It the master controller is moved to position 3, an energized contact member 34 engages a control finger from which point circuit is completed through a conductor B6 and the actuating coil of the switch R3 to the conductor 27. lf the controller is moved to position Ll, the energized contact members 24 engages a control linger 37, whence circuit is completed through a conductor 3S and the actuating coil of the switch R* to the conductor 2T. Substantially simultaneously, the contact member 34 disengages the control finger 35. In position 5, the actuating coil. of the switch R1 is again energized through the engagement of an energized contact member 39 with the control finger 30, and the actuating coil of the switch R3 is likewise energized by the engagement of the contact member 39 withthe vcontrol finger 35. The coil ol the switch R" is denergized at the same time by reason of the disengagement of the contact member 24 with the control. finger 3 In this way, the various resistor switches are manipulated to gradually accelerate the motors until, in position 5 oi the master controller, the motors are connected in full series relation, with all of the accelerating resistors excluded.

During the transition from series to par! allel relation of the motors, the contact member 24. engages a control linger 40, from which point circuit is established through conductor 4l and the actuating coil ol the switch Ur to conductor 2G. The switch R1 is also opened by reason of the disengagement of the contact member 39 with the control finger 30.

In position (i, the switch S is opened by the disengagement of the contact member 24 and the control finger 23, and the actuating coil ot' the switch P is thereupon energized from the conductor il through an interlocking contact member marked S-out.

In position 7, the switch R is opened through the disengagement ot' the contact' member 39 with the control linger 35, and switch R" .1s closed by the rcengagement of the contact member 24. with the control finger 37. In position 8, the switchRl is closed y included in the motor circuit, upon the ini-y tial parallel connection of the motors, is again gradually excluded from circuit until, in position 9, the motors are disposed in full parallel relation, with all the accelerating resistors short-circuited.

The actuation of the switches, that isl caused by the operation of the master controller to the position 9, produces a certain mstantaneds increase 1n the motor current,

as will be understood, whereby the limit switch L is actuated to its upper positionu to break the circuit of the actuating coil of the iield change-,over switches. However, vwhen the motor, current has` decreased to a value which fis determined bythe characteristics of" thev limitswi'tch L, the movable contact member ot, the switch drops to itsylower position, r whereupon a circuit is established from the conductor 20 through interlocking Contact members marked, respectively, IL-in, R3-in, and R1-in, the coperating stationary and movable contact members 43 of the limit switch L and the actuating coil of the field change-over switches to ground. Upon the operation of the field change-over switches, their actuating coil is vr'connected to alzholding circuit from the conl the interlocking contact jductor 19, through member marked FE the 'energizationpf the coil vthus being thereafter independent of the operation of the limit switch L. It will thus be observedthat the field change-over switches are not actuated from their fullfield position to their normal-field position until the full accelerating effect of the total exclusion of the resistor AR is obtained, whereby the smoothness and efficiency of the motor acceleration is increased.

It should be noted that my invention embodies-,simple and ineXpensivemeans for providing field control p I, type of control system, by the mere addition of suitable devices withoutthe necessity of making any inherent modifications of the control apparatus which would otherwise be l employed.

If'do. not Wish to be restricted to the specilic circuit connections and arrangement of ,/p'arts herein set forth, but desire that only -l such limi/ tations shall be imposed as are indicatedy in the appended claims.

' I claim as my invention:

l. In a control system, the combination with a supply circuit, anda plurality of electric motors severally provided with armatures and field windings, of means for effecting series-parallel acceleration ofsaid motors, and means dependent upon predetermined circuit. connections and current conditions for varying the active portionsfof said field windings'.

-2. In a control system, the combination "with a supply circuit, and a plurality of electricymotors severally provided with armatures, and field windings, of means for eii'ecting series-parallel acceleration of said motors, and`v means dependent upon predetermined currentvconditions for automatically varying the strength of the field winding after the motors are disposed in full parallel relation. a control system, the combination in any suitable 'l parallel acceleration of said motors, and automatic switching means operative under relatively low motor-current conditions only after the motors are disposed in full parallel relation for excluding portions of said field windings from circuit.

4. In a series-parallel system, the combination with a supply-circuit, and an electric -`motor provided with an armature and a series-connected subdivided field winding, of a plurality of motor-circuit switches including certain switches that are employed only during parallel relation of the motors, severally provided with closing coils, a switching device for varying the active portions of the field windings and having, an actuating coil, a limit switch actuated in accordance with the motor current and having auxiliary contact members included inthe energizing circuit of said actuating coil under relatively low motor-current conditions, and interlocking means associated with one of said certain switches for completing the circuit of said actuating coil, whereby the active portions of the field windings are varied only after the motors are disposed in full parallel relation and the motor-current has decreased to a predetermined value.

5. In a control system, the combination with a supply circuit, an electric motor provided with an armature and a series-connected subdivided field winding, and a plurality of accelerating resistors,l of a plurality of motor-circuit switches, including resistor short-circuiting switches, severally provided with closing coils, an auxiliary control system for governing said closing coils to start, and gradually exclude said resistors to accelerate said motors, a switch biased to exclude a portion of said ield winding from circuit when certain switches, including said short-circuiting switches, are closed, and an actuating coil for said biased switch that is connected to have its current vary with the motor current and adapted to maintain said switch open when the currentv 'exceeds a predetermined value,

In testimony whereof, I have hereunto subscribed my name this 29th day of May CLARENCE RENSHAW. Witnesses: C. L. DAVIS,

B. B. HINEs. 

